1. Field of the Invention
This invention relates to a device for rendering an emergency-lock mechanism when lock is unnecessary in a retractor provided with an emergency-lock mechanism in a safety seat belt system for a vehicle.
2. Description of the Prior Art
Numerous safety seat belt systems for vehicle in which, during normal running of the vehicle, the draw-out and withdrawal of webbing from a retractor is kept free and during a sudden variation in speed of the vehicle body resulting from collision or the like, the draw-out of the webbing is locked to restrain a seat occupant have been proposed and put into practical use. In such an emergency-lock mechanism, two types of means for sensing a sudden variation in speed of the vehicle body resulting from collision or the like have been used, namely, the webbing draw-out acceleration sensing type which senses a variation in draw-out speed of the webbing and the vehicle body acceleration sensing type which directly senses a variation in speed of the vehicle body. In case of a retractor provided with an emergency-lock mechanism of the former type, namely, of the webbing draw-out acceleration sensing type, the emergency-lock mechanism works even when the webbing is rapidly drawn out during the wearing of the seat belt, thus making it difficult to manipulate the webbing and for this reason, a mechanism for rendering the emergency-lock mechanism inoperative by energizing an electromagnet or the like when emergency-lock is unnecessary has already been proposed. However, in case of a retractor provided with an emergency-lock mechanism of the latter type, namely, of the vehicle body acceleration sensing type, it has not posed so great a problem to render the emergency-lock mechanism inoperative. This is because the retractor has heretofore been attached to the vehicle body. However, in case of the passive safety seat belt system whereby the seat occupant is caused to wear the safety seat belt independently of his or her will, it becomes necessary to attach the retractor to a movable portion of the vehicle body such as the door or the like and the emergency-lock mechanism may undesirably operate during the movement of such movable portion.